Multitasking: My Computer Can Do It, Why Can’t I?

Well, actually computers can’t multitask. What computers are good at is two things that give them the appearance of multi-tasking. First off, they can store their short-term memory at any time and then recall it exactly as it was. No data loss, no rework — the computer just picks it up right where it left off and keeps going. The second thing is that computers are able to switch between tasks extremely fast. One millisecond it’s calculating π and the next it’s pulling up Google Maps in your browser. In between it checked on the status of its memory or, if the CPU was too hot, contemplated briefly if the toaster in the break room is single.

Now try that with your human brain.

First try and store your memory. Look at a sequence of sixteen numbers, such as 43, 57, 239, 1, 32, 999, 0, 87, 58, 10, 91, 385, 872, 21, 3, 74. Take a good long look at them. Now go get a cup of coffee, check your email and like a couple of posts on Facebook. Okay, what were the numbers?

Now how good at are you at task switching? Grab a book, any book. Read half a page. Now imagine you heard the doorbell ring. In the middle of a paragraph, close the book, set it down and go check the door. No one’s there, so you go back to your book. You forgot to put a bookmark in (storing your memory) and even when you find the page again, you have to scan over the page until you find the place where you left off. Between the time you took to answer the door and to find your page and sentence again, how much time did you just use?

Multitasking is a myth. Even computers can’t do it. (Okay, technically a multi-CPU computer can, but we don’t have multi-brain people, so let’s stick with the comparison to single-CPU computers). Instead the illusion of multitasking can be attributed to how quickly you can switch between tasks coupled with how much you can remember.

I don’t need to belabor for you the limitations of human memory. Suffice it to say that humans have limited short-term memory (between 4+/- 1 and 7+/-2 items) and our recall of long term memory is impeded by delay, interference and accessibility issues. See the Wikipedia article on Short-Term Memory and this article on “Forgetting” in Psychologists World if you want to read more on that.

What I really want to focus on is the problem of task switching.

Task Switching

Switching between various tasks (also known as context switching) has significant costs associated with it. Two of the leading ones are:

  • Loss of Productivity: In his book “Quality Software Management: System’s Thinking,” Gerald Weinberg visualizes the cost of context switching in the chart below. When you change tasks, your brain has to change the context it is working in. The more you change contexts, the heavier the cost.
  • Lower Quality: Task switching also leads to more errors, with a popular infographic on “The High Cost of Multitasking” by citing up to 50% more errors when you multitask (the data was probably pulled from this report).

Getting the point home

Odds are that, if you are reading this blog, you already understand this concept at least in part. The challenge, of course, is how to get “those other guys” to see the light. When working with teams and management, I like to boil it down to very simple hands-on exercises or examples. Here are a few things you can reach for to try and demonstrate the value of not multitasking.

1. Hands-on Exercise

Nothing beats first-hand experience. To provide the first-hand experience of the illusion of multitasking, I use a version of an exercise called the “Secrets of Multitasking,” which I’ve revised and updated over the years. It’s a five- to ten-minute exercise requiring only blank paper and ballpoint pens. The short form is you have participants try and produce multiple things at the same time, then have them do one thing at a time and then compare the time results. Inevitably, participants realize that doing multiple things at the same time takes much longer than the total time of working several tasks one after the other. I have used this exercise with five to twenty managers and decision makers to help them see the dangers of multitasking first hand in real time.

You can find a full write up on how I run this exercise here.

2. Visuals

A picture is worth a thousand words. While nothing beats hands-on experience, images can form a lasting impression and are something people can take away from the conversation. The challenge with hands-on exercises is that you have to get them hands-on, which is a non-trivial task sometimes.

When working with a national insurance carrier, the challenge I had to tackle was how to get the message beyond the teams and their direct managers. The chief Product Owner came to my training and he absolutely got the dangers of multitasking. Only he couldn’t just tell his stakeholders, “Trust me, it doesn’t work.” Besides, not everyone is comfortable with asking their bosses to do an exercise. I came up with class takeaways that could be presented to those stakeholders “too busy” to come to training or do a five-minute exercise.

The two visuals above, Weinberg’s chart and the infographic excerpt, are two of the takeaways I provided. Below is yet another. This one-page visual demonstrates the theoretical production of three machines that build different kinds of cell phones, accentuating the difference between sequenced and simultaneous work. A full slide deck presentation on this theme can be downloaded here.

3. Be the Mirror

Like good cream, excellence has a way of rising to the top. If you can practice “right tasking” yourself, you can be the example others can follow. When you, or your team, start getting more done, look happier, and are more engaged, there is a good chance people will start to ask why. You may not be able to change the whole organization. Don’t try. Instead run experiments. When they are successful, show the results and try and run a larger experiment the next time. Rinse and repeat.

How do you and your teams get more done? Do you limit your WIP? Why or why not? Let me know in the comments below!


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